In the past, display devices that display a moving picture such that the moving picture can be stereoscopically viewed (that is, perform stereoscopic display) have been used. For example, a display device can cause a moving picture to be stereoscopically presented by imaging a left picture and a right picture having a parallax therebetween as pictures configuring the moving picture and displaying the left picture and the right picture such that the left picture is viewed by the left eye, and the right picture is viewed by the right eye. At the time of display, the display device alternately displays the left and right pictures in a time division manner, and an active shutter glasses scheme in which left and right shutters are operated by dedicated glasses in synchronization with a switching timing thereof is used.
In such display devices, a technique of combining closed captions with a moving picture has been proposed (for example, see Patent Literature 1). Closed captions are subtitles generated independently of a moving picture so that a display device can perform control, for example, such that subtitles are displayed or not displayed. On the other hand, subtitles that are supplied in a form combined with a moving picture and hardly controlled to be displayed or not displayed by a display device are referred to as open captions.
When a display device adds closed captions, the closed captions are considered to be stereoscopically displayed as well. Commonly, when subtitles are stereoscopically displayed, a planar subtitle picture indicating subtitles is generated and the subtitle picture is converted into a picture to be stereoscopically displayed using a 2D-to-3D conversion technique. The 2D-to-3D conversion refers to a technique of converting a picture that is not stereoscopically displayed into a picture to be stereoscopically displayed. Specifically, a technique of generating two pictures by causing a normal planar picture to deviate rightward and leftward in a horizontal direction and using one of the two pictures as a left picture to be viewed by the left eye and the other as a right picture to be viewed by the right eye is used (for example, see Patent Literature 2).